Railway traffic controlling apparatus



Sept. 25, 1951 c. w. FAlLoR x-:TAL

RAILWAY TRAFFIC CONTROLLING APPARATUS 5 Sheets-Sheet l Filed Jan. 15, 1948 Sept. 25, 1951 c. w. FAlLoR ET AL 2,568,997

" RAILWAY TRAFFIC CONTROLLING APPARATUS Filed Jan. l5, 1948 5 Sheets-Sheet 2 Sept. 25, 1951 c. w. FAILOR ET AL #f 2,568,997

RAILWAY TRAFFIC CONTROLLING APPARATUS Filed Jan. 15, 1948 l 5 Sheets-Sheet 5 I7 jf. INVENToRs.

' ClzaPIes Wlazlop and John endepsall THEIR TTHNEY Sept. 25, 1951 c. w. FAILOR ET'AL.

RAILWAY TRAFFIC coNTRoLLING APPARATUS Filed Jan. l5, 1948 JNVENTORS.

depyan Cimffe ailor and Patented Sept. `25,

UNITED STATES PATENT OFFICE'.

RAILWAY TRAFFIC CONTROLLING APPARATUS Pennsylvania Application January 15, 1948,r Serial No. 2,398

claims.

Our invention relates to railway tra'ic controlling apparatus, and particularly to apparatus embodying coded track circuits at an interlocking plant for controlling wayside signals and cab signals,

At an interlocking plant, usually most of the track sections within interlocking limits are short or include a portion of a crossover or other auxiliary track. It is therefore obviously imperative that the track circuits for these sections shall have high shunting sensitivity and shall be quick shunting. It is also important that adequate protection be provided against a momentary loss of shunt of any track circuit. Coded track circuits inherently have higher shunting sensitivity than non-coded track circuits with the same normal voltage, and provide greater protection against a momentary loss of shunt than non-coded track circuits.

Where cab signals are operated Within interlocking limits, it is particularly important that the track circuits shall be quick shunting so that the cab signals shall respond quickly to any change in traic conditions. It is also important that adequate overrun protection be provided, so that if a train should pass a stop signal for a route which conicts with a route for which a proceed signal is being displayed or which is already Aoccupied by another train which has been given a proceed signal indication and is therefore authorized to enter its route, the authorized train will at once be given a restricting or a proceed cab signal indication according to the location of the authorized train in its route at the time an unauthorized train passes the stop signal, and the unauthorized train will continue to receive a restricting cab signal indication.

One feature of our invention is the provision of a novel and improved arrangement for applying cab signal control energy to the relay end of a track circuit for a track section over which traliic normally moves in both directions.

Another feature of our invention is the provision of an arrangement embodying a floater track relay for giving overrun protection.

Another feature of our invention is the provision of an arrangement for controlling an approach stick cab signal relay so that it will not become energized in response to an unauthorized train passing a stop signal onto its route.

Another feature of our invention is the provision of an arrangement for controlling track circuit current for controlling the cab signal of an authorized train to display a proceed or a restricting indication according as the authorized train is ahead of or is back of a point at which an approaching unauthorized train would conflict with movement of the authorized train, at the left, and Figs. 1c and 1d constitute diagrammatic views showing one form of apparatus embodying our invention, in which coded track circuits are provided with interlocking limits at an interlocking plant for controlling wayside interlocking signals and for controlling cab signal control current; Fig. 2 is a diagrammatic view showing a modication of a portion of the apparatus shown in Figs. 1a and 1b for using steady alter nating current for resetting a track circuit for a code change point in a cab signal control system; and Fig. 3 is a diagrammatic view showing a modification of a portion of the apparatus shown in Fig. 2 for resetting a track circuit for a code change point by coded current of a given characteristic such that it will not operate cab signals.

Similar reference characters refer to similar parts in each of the views.

In each of the views, contacts operated by the various relays or other devices are identiiied by numbers, such numbers having distinguishing prexes from which they are separated by a dash when the contacts are shown apart from the relay or other device by which they are operated. The prefix for each of these contact numbers comprises the reference character for the respective relay or other device by which the contact is operated. For example, contact 25TM-92, shown in the circuits for relay 2ITV in Fig, lc, is identified by the number 92 separated by a dash from the prex 25TM Which is the reference character for relay 25TM by which this contact is operated. Some contacts shown in the drawings, but which are included only in circuits which are not traced in this specification, are identified by the reference character for the relay or other device by which they are operated, followed by a dash Without a number after the dash.

For example, contact 23TV-, shown in the circuit for relay 23TV in Fig. 1c, is identified by the reference character 23TV for relay 23TV by which this Contact is operated followed by only a dash.

Referring rst to Figs. la, 1b, le and 1d, a portion of a track layout is shown, in Figs. 1a and 1b for an interlocking plant provided with crossovers, single switches, and interlocking signals. We shall assume that the left-hand end of the track layout, as shown in Fig. la of the drawings, is the west end, and that, hence, the opposite or right-hand end of the track layout, as shown in Fig. lb of the drawings, is the east end.

Traic movements in thev eastbound direction are governed by signals 4L, ML, 261.1 and 26Lc. Traffic movements in the westbound direction are governed by signals 4R, 24R, GRa, GRD, and 2BR..

Each of the signals 4L, 4R, 24L, 24R, and 26T.;v

has an upper arm or unit a and a lower arm or unit b. Each ofthe signals may be of the position light type or of any other suitable design.

At the west end, an auxiliary track T is connected with a section 2 IT of an eastbound main track IT by a switch 25. At the east end, a

second auxiliarytrack ET is connected with eastbound main'track `IT by a second,r switch 23. Two other main tracks, designated by the reference characters 2T and 3T, are interconnected by a crossover having a switch Il at its west end and a switch EI'I at its east end. Tracks IT and 2T are interconnected by a crossover having a switch 2| at itsI west end and a second switch E2! at its east end, and are also interconnected by a crossover' having a switch I9v at its west end and a switch EIS)l at its east end.

Track T is divided by insulated joints 5 to form a section T. Section 25T is provided with a track circuit including a suitable source of current, such as a battery Sfconnected across the east end of section 25T through contacts I and 8 of a coding device WISQCT, and a'code following track relay 25,'1?, connected across the west end of the section. Coding device WISOCT Ais constantly energizedby a suitable source having terminals Band N, and therefore this codingv device repeatedly operates its contacts 'l and 8 between their front and back points at a fre-` quency whichV may be 180 times per minute.

Track IT is divided by insulated joints 5 to form sections IST, 24T, and 23T. Each of these sections is provided withea track circuit which is` supplied with coded direct current at its east end by a source such, for example, as a battery 6 connected through contacts 9, and I@ of a code repeater relay, designated `by the reference character CTM preceded by the numeral for its track section, such as ZICTM for section 2IT, and includes a code following track relay, such as relay ZITR which is similar to relay 25TH, connected across its west end.

A oater track relay ZSXTR is connected across the rails of section 2IT adjacent switch 25. A resistor 25T is connected around a pair of insulated joints 5 which is adjacent, and to the west of, switch 25, so that resistor 251- is at all times in series with the portion of the track circuit for section ZIT which is west of thispair Aof insulated joints 5. An eastbound train on section 2IT, therefore, does not deenergize relay ZEXTR until the train has passed the point at which resistor 251' is connected with section 21T.

The track circuit for each of the sections IST, 2 IT, and 23T also includes the secondary winding d of a cab signal transformer such, for example,`

as transformer 2 ICF shown in Fig. 1b for section 2 IT, connected in series with battery G across the east end of the section.

Track 2T is divided by insulated joints 5 to form a section IIT. Section I'IT is supplied with coded direct current at its east end similarly to sections IST, 2IT, and 23T, as just described, but the arrangement at the west end of section IIT is different from that at the west end of sections IST, 2IT, and 23T. Track relay I'ITR is connected across vthe west end of section I 1T through the back points of contacts II and I2 of a code following transfer relay IIWCTM. The front points' of these contacts of relay IWCTM at times close a circuit path across the west end of section HT through secondary winding d of a cabsignal transformer I'IWCF.

A -[ioater track relay ISXTR is connected across section I-'IT adjacent, and east of, switch I9, and a second oater track relay ZIXTR is connected across section HT adjacent, and west of, switch E2 I.. A resistor Ir is connected with section I`IT at a pair of insulated joints 5 which Ais adjacent, and east of, switch I9, so that resistor I91' is at all times in series with the portion of the track circuit for section IIT which is west of resistor I91'. A resistor 2 Ir is connected with section IT at a pair of insulated joints 5 which is adjacent, and west of, switch E21, so that resistor 2Ir is at all times in series with the portion of the track circuit for section IIT which is west of resistor 2Ir.

Track 3T is divided by insulated joints 5 to form a section I3T. Section IST isprovided with a track circuit which is similar to that for section I'IT except that the battery is at the west end, and the track relay is at the east end of section IST. Secondary windings d of cab signal transformers are connected across the ends of section IST similarly to those for section IIT.

From the foregoing description, it follows that each of the sections I3T and I lT is provided with apparatus for supplying cab signal control energy to its west end as well as to its east end for controlling cab signals for Westbound trains as well as for eastbound trains, whereaseach of the sections of track` IT is provided with apparatus for supplying cab signal control energy to the east end only for controlling cab signals for eastbound trains only, and section 25TV is not supplied with cab signal control energy for either direction of traic movements. Therefore, any train moving over section 25T will never receive a proceed cab signal indication, but will alwayshave a restrictivel cab signal indication.

Energization of primary winding m of each of the cab signal transformers is effected by a circuit Which includes the front point of a contact of an approach stick cab signal relay designated by the reference character TV with a numerical prefix which is the same as that for the associated track section. Each of the cab signal relays is normally deenergized, and therefore each of thecab signal transformers is normally deenergized, and its primarywinding m is connected in a closed path which includes a back point of `the contact of the associated `cab signal relay.

For example, energization of cab signal transformer IICF, shown in Fig. 1b, is effected by a circuit which is controlled by the front point of contact NTV-ls, but, since relay IITV is normally deneergized, primary winding m of transformer I ICF is normally included in a closed cir. cuit path through the back point of contact IPTV-18. Similarly, energization of primaryA amasar,

'winding m of transformer I'IWCF, shown in Fig.

la.' is effected by a circuit which is controlled by the front point of contact IIWTV-BB, but since relay Il'WTV is normally deenergized, primary winding m of transformer I'IWCF is normally included in a closed path through the back point of contact IIWTV-BG.

When relay I'IWTV is energized, winding .m of transformer I 'IWCF is controlled in multiple with winding m of an auxiliary transformer I'IXF in .a circuit which is controlled by a detector relay IIFSA, by a switch lever I'IV for controlling operation of switches E I'I and I'I, and by one of the code transmitting devices which operate their contacts at a frequency of 75, 120, or 180 times per minute and are designated 'I5CT, IZUCT, and IBUCT, respectively. The code transmitters are selected by a traiic relay ZWH in accordance with traic conditions on track 2T West of sec- Ition I'IT, When transformer IIXF is thus energized, relay IIWCTM is energized from the secondary winding d of this transformer, through a rectifier RC which comprises asymmetric units il, i2, i3', and i4, which may be lof the well-known copper oxide rectier type.

Relay ISECTM and transformer I3ECF for the east end of section I3T are controlled similarly to relay ITWCTM and transformer I'IWCF, respectively, as just described.

The track switches shown in Figs. 1a and lb may be operated in a well-known manner by means controlled by manually operable levers. Operation of switches I'I and EIT, for example, between their normal and reverse positions, may be controlled by switch lever I'IV which has a normal position n for controlling operation of switches I'I and EI'I to their normal positions in which they are shown in the drawings, and has fa reverse position r for controlling operation of switches II and EII to their reverse positions. Lever I'IV also has a normal lock Ipositions b and a reverse lock position d.

Contacts operated by each of the switch levers, as shown in Figs. 1a, 1b and 1c of the accompanying drawings, and also contacts operated by signal levers shown in Fig. 1d which will be referred to later in the specication, are shown as circles in which are placed reference characters to show the positions of the levers in which the contacts are closed. Contact 84 of lever IIV shown in the lower left-hand portion of Fig. 1a, for example, is closed when lever I IV is in its normal position n or in its normal lock position b or at any other point between these two positions.

First detector relays I3FSA, 23FSA and ZEFSA are energized by circuits which are controlled by track relays ISTR, ISTR, ZITR, 23TR and 25TR, respectively, which are similar to the circuit shown in Fig. la for energizing relay I'IFSA by the front point of contact HTR-28. Second detector relays I3BSA, ISBSA, ZIBSA, 23BSA, and 25BSA are energized by circuits which are controlled by associated track relaysv and rst detector relays, having the same numer-V ical prex, which are similar to the circuit shown in Fig. la for energizing relay I'IBSA through the back point of contact HTR-28 and through .a front contact of relay I 1FSA.

First slow pick-up relays I3BSAM, IBBSAM, 2 IBSAM, 23BSAM, and 25BSAM are energized by circuits controlled by second detector relays, having corresponding numerical prexes, which are similar to the circuits shown in Fig. 1a for energizing relay IIBSAM through a front contact 32 of relay I'IBSA. Second slow pick-up relays ISFSA, 2 l FSA, v

fixes, which are similarto the circuit shown in Fig. 1a for energizing relay I'ITM through a front contact 3'3 of relay IIBSAM.

Code repeater relays l I3CTM, IQCTM, ZICTM, and 23CTM are energized by circuits Icontrolled by track and detector relays, having corresponding numerical prefixes, and by code transmitter MIIlCT, ,which are similar to the circuits shown in Fig. 1a for energizing relay I'ICTM by code transmitter MIBDCT and by detector relays I'IFSA and I'IBSA.

Circuits for controlling the approach stick cab signal relays are shown in Fig. 1c. These relays are controlled in part by signal control relays such, for example, as relays 24LaI-I and 24LJ, as shown for relay IITV.

Signal 24L may be controlled in a well-known manner by relays 24LaH and 24LJ to ldisplay a given proceed indication when relay 24LaH is energized, and to display a given different proceed indication when relay ZQLJ is energized. Relay 24LaH is controlled inY part by a contact of. a track indication relay 24LA in a circuit, only a portion of Whichis shown in the drawing.

The signal control relays may be controlled in.l part manually, as well as in part automatically by traffic conditions in advance of the signals. which they control.

Pick-up and stick circuits for a code selecting stick relay 3U are also shown in Fig. 1c.

In Fig. 1d, pick-up and stick circuits are shown for track stick lrelays ISTS, I'ITS` and 2ITS.. The pick-up circuit for each of these relays includes a normal or n contact of a control lever for a signal which governs traiiic movements over a corresponding track section. Y

Each of the signal control levers has a normal position n and two reverse positions f and r for controlling eastbound or westbound signals respectively. Y

Also in Fig. ld, control circuits are shown for track indication relays 4LA, 24LA and ZGLA.

Control circuits for floater repeater relay ZIXTM and floater stick relays 25XTM and 25S, and for oater detector relays ISXFSA and ISXBSA are also shown in Fig. 1d.

Referring next to Fig. 2, a stretch of track Y of an electric railway is shown, on which the propulsion current for train operation may have a frequency of 25 cycles lper second. Track Y is shown divided by insulated joints 5 to form a block a-c. Impedance bonds 2'I of a wellknown type are provided at the ends a and c of this block.

A signal IS governs -traic movements into block a-c, and a second signal 2S governs trame movements from block a-c into the next block east of block a-c. Signal `2S is an interlocking signal, and is therefore shown normally at stop.

Signals IS and 2S may be of the position light type or of any other suitable design.

A portion of an operating circuit for signal 2S ausgew? rails. of block at 'a point b which is known as a code change point-1 for cab'signals. Relay XTR is therefore also energized from transformer IF through the rails of portion b-c of block a-c.

A detector relay FSA is control-ledby a circuit which includes the front point of a contact,- of relay XTR. A second detector relay BSA'is con-- trolled by relays XTR and FSA.

Primary winding m of transformer' IF is at times energized througha back point of contact II4 of relay 2H, and through contactsA ofl relays FSA and BSA and a code transmitter CT. Pri'- mary winding m of transformer IFis also at times energizedthrough the front point of contact IIlIA of relay 2H by a circuit controlled by relay ZTR and a code transmitter I-BUCT;

Referring now to'Fig. 3, a spekzcial coding device XCT is here provided for coding they current at a frequency to' which the cab signaling appartus will not respond. The coded current thus produced may be' of a low frequency such, for example, as cycles per minute, or it may be of al limp code such as short on` and long on". Detector relays XFSA and XBSA are controlled similarly to the manner in` which' relays FSA and BSA are shown controlled1 in Fig'. 2. The purpose of relays XFSA and' 1035A in Fig. 3 is' to serve' as checking means" for the' operation of device XCT, so that if contact I2!) of device XCT should be; come constantly closed, the circuit for primary winding mA of' transformer'iF will be' opened at contact I2I of relay'XBSA. Current codedI by' device XCT is suppl'edito the" primary Ywindingm of transformer IFv when relays BSA and'J 2H, shown in Fig. 2; are deenergizedl Having described', in general; the' arrangement and control of the' apparatusshown. 'by the accompanying drawings, we sha'll now describe, in detailits operation.

As shown by the drawings, allpartsare in their normal condition, that is, the tracksections are unoccupied and therefore. all track relays' are energized by coded current; each` ofthe signals shown in Figs. la'and 1b and'signal 2S shown in Fig. 2 are indicating stop; signal' IS shown in Fig. 2 is indicating caution; eachof the switch and signal levers is in its n-positionz'eachof the coding devices CT is constantly' energized; and is therefore repeatedly moving contactsbetween the front and back points; each of' th'ecab signal transformers CF; andeach-of the auxiliary transformers XF is deenergized; each` ofthe traic relays EH and WH is-energized by current of normal polarity; each ofthe detector ref lays FSA and BSA; each of the; slow pick-up relays BSAM and TM, each of the code repeater relays CTM, relay 3U, each of the track` stick relays TS, each of the traclrindication relays LA,

each of the oater stickand repeater relays XTM, and relay .25s are'energlzed; and relays- I3ECTM and I'IWCTM, eachof the cab signal' relays TV, and relay 2H, shown inl Fig. 2, are deenergized.

In Fig. 1a, thecircuit by-which relay25TR'is periodically energized passes from the positiveterminal of a battery 6', through-thebackfpoints of contacts Iand`-8 offcoding device `EIBIICTA in multiple, upper rail of section 25T," as shownin` the drawing, Winding of relay TH, and lower-v rail of section 25T, back-.to\thenegativeterminal of battery 6I In orderto dimifnish'the road bed storage battery effect; tlerailsI of sectlonl 25T are periodicallylshuntedby the' front-points' of contacts 'I and Bioffcoding device =WI80CT 8 passes' from the positive terminal of a battery 6. through the back points of contacts ZICTM-S and 2ICTM-I0 in multiple shown in Fig. 1b, upper rail of section 2IT, as shown in the draw# ing, to switch 25, thence by the lower rail to the winding of relay ZITR, upper rail of section 2IT, through resistor 251 to the lower rail, and secondary winding d of transformer 2ICF back to battery 6. Floater track relay 25XTR is ener-y gized by a circuit which is similar to the one just traced for relay ZITR except that it does` not include resistor 2'51 and does not include' the rails between resistor 251' and signal 26L. Relays' ISTR and 2'3TR are also energized by circuits' which are similar to the circuit traced for'relay' 2`ITR except that they do not include a resistor such asI resistor 251". t

The circuit by which relay IITR' is energized passes from the positive terminal of a batteyli, through the back points of contacts I'I'C'IM-s and I'ICTM-Io i'n multiple', to the upperV rail of section ITT, as shown in the drawing, resistor I`91 to the lower rail, resistor 2Ir to the upper rail, winding of relay I'ITR', through the back points of contacts II and' I2 of relay ITWCTM in multiple with each other, lower rail of section 11T to switch E2I, thence by the upper rail to switch I9, thence to the lower rail, and through secondary winding d of transformer HCF back to the negativeside of battery 6L Relay IS'XTR is energized by a circuit which is the same as the circuit just traced for relay IITR to the point at which relay ISXTR is connected across the rails of Vsection IIT. Relay 'ZIXTR isenergized. by a circuit which is similar to the circuit traced for relay ITI'R except that it does notinclude resistor 2I'r and doesnot include theportionof section HT which is west ofY resistor 2Ir.

The circuitby'which relay` I3TR.-is energized' is similar to the circuit traced for relay I`ITR- except that it does not include any resistors.-

. The'circuit by which relay I'IFSA is energizedf as shown in Fig,` la, passes from terminal Bp throughthe front point of contact I1TR-2B,and the winding of relay I'IFSA in multiple with` a. resistor 29 and the high resistance direction of' an asymmetrictunit 30'tovterminal N. The cir" cuit by which relay I'IBSA is energized passes from'terminal B, through the back pointv of'contact.I1TRf28, and contact 3| of relay II'IFSA and the winding of relay I'IBSA, in multiple with a" resistor 29 and the high resistancev direction of' an. asymmetric unit 30 to terminalA N. Relay I-IBSAM is-energized byan obvious circuitc'ontrolled by contact 32l of relay ITBSA. Relay HTM is energized by ank obviousA circuit controlled by 4contact 33 of relay I'IBSAM: Relay IICTMis periodically energized by a circuit'pass ing' from terminal B, through-contact 34 of -coding. device MICT, frontw point of contact 36'? of relay. 'I'IBSA, and the windingof'relay. IICTM7 in multiple/with resistor 2'9and the high re' sistance direction of an asymmetric unit 30 toterminal N. Y

Relay 3U, shown in Fig. 1c, is energized by' a circuit passing fromltermin'al'B," through'conV` tacts ISV-31 and ZIV-38, contact 39 ofi' lever of contact 23TV-4-2'; and the winding ofrelay- 3Utotermin`al N.'4

lBc'athapiclrLup anda stickvv circuit are closedl for energizingI each of' the track stick" relays-l la'rs'.' |1'r's,'and :irs-shown in Fig; 1a.l 'nuri The Lcircuitlby: which =relay1 2I'-IItfislenerg-izled 75 picklupcircuit for-'relay d'I 3T"S,=for example; passes 9 from terminal B, through contact HTM-43, contact 46 of lever 4V, and the winding of relay I3'IS to terminal N. The stick circuit for this relay passes from terminal B, through contact |3TM-43, contact l3TS-45, and the Winding of relay |3TS to terminal N. The pick-up and stick Acircuits for relays HTS and ZITS are similar to those just traced for relay I3TS, and can therefore be readily traced on the drawing.

Track indication relay ALA, shown in Fig. 1d, is energized by an obvious circuit controlled by contact I 3TS-4'I. Relay 24LA is energized by a circuit passing from terminal B, through contact HTS-41, contact ZGLA-d in multiple with contact ISV-49, contact ALA-50 in multiple with contact I 'lV-5|, and the Winding of relay '24LA to terminal N. Relay ZBLA is energized by a circuit passing from terminal B, through contact UTS-41, contacts NTM-52, 23TM-53, 2.0

and 21V-59, and the winding of relay ZBLA to terminal N.

Both a pick-up and a stick circuit are closed for energizing relay 25S, shown in Fig. 1d. The

frequency of 75 timesper minute, passing from terminal BX, through contact 19 of coding device E'I5CT, contact 'I3 of relay 2El-l closed in the reverse position, and thence by the remainder 'of I the path previously traced for energizing'windpick-up circuit for this relay passes from ter- 2llLaH, to display a proceed indication. An east- ,we

bound train, upon passing signal ML, deenergizes relay HTR, thereby causing relays HFSA, HBSA, HBSAM, I 1CTM, and HTM to be deenergized in the order named.

With relay 24LaH energized to control signal 24L to display a proceed indication at the time the eastbound train enters section HT, cab signal relay HTV becomes energized by a circuit passing from terminal B, through contact HTM-64, contact 65 of relay ZQLaH, and the Winding of relay HTV to terminal N. Relay HTV, upon becoming energized, closes its own stick circuit Which is the same as the pick-up circuit just traced except that it includes contact HTV-61 instead of contact 65 of relay 24LaI-I.

Deenergization of relay HTM causes contact HTM-43 to open the circuits described for relay HTS, so that relay HTS becomes deenergized. Relay HTS, upon becoming deenergized, opens at its contact HTS-41, the circuits previously traced for relay 24LA. Relay MLA then opens its contact MLA-63, causing relay ZLaI-I to become deenergized. Relay HTV, however, remains energized by its stick circuit previously traced. With relay HTV energized, cab signal transformer HCF1 becomes energized by a circuit passing from terminal BX of a suitable source of alternating current, through contact 12 of coding device EI8IJCT, contact i3 of relay ZEH closed in the normal or left-hand position, contact 14 of relay ZEH, contacts ZIV-l5 and ITV-16, contact 'H of lever ISV, front point of contact HTV-18, and primary Winding m of transformer HCF to terminal NX of the same source of alternating current. With transformer HCFl energized, cab signal control current is supplied to section HT in the circuit previously traced for energizing relay HTR. This cab signal control current is coded at a rate, for example, of 180 times per minute, to control the cab Vtimes per minute.

ing m of transformer HCF by current coded 180 With cab signal control current coded at a rate of '75 times per minute being supplied to track section HT, the cab signal on the train Would display a corresponding proceed indication.

HFSA becomes constantly energized by. its circuit previously traced. With relay HFSA now energized, relay HCTM becomes energized by steady current passing from terminal B, through contact 35 of relay HFSA, back point of contact 36 of relay I 1BSA, and the winding of relay HCTM` in multiple With resistor 29 and asymmetric unit 3!) to terminal N. Relay HCTM, upon becoming energized, opens the circuit previously traced for relay HTR through contacts HCTM-9 and HCTM-l0, causing relay HTR to become deenergized. With relay HTR deenergized, relay HBSA becomes energized by its circuit previously described. With relay HBSA energized, the circuit previously traced for relay HCTM through contact 34 of coding device MI CT is now again closed, causing relay HCTM to be again periodically energized and to thereby restore the track circuit for'section HT to its normally coded operation.

When relay HTM now becomes energized, relay HTV becomes deenergized, causing transformer HCF to also be deenergized and to therefore discontinue the supply of cab signal control current to section HT.

v We shall now assume that all parts of the apparatus are again in the normal condition, and that signal 24R is controlled by energization of relay 24RaH to display a proceed indication for a Westbound train. When the westboundl train passes signal 24R, relays HTR, ISXTR, and 2 IXTR become deenergized.

With relay 24RaII energized for controlling signal 24R to display a proceed indication at the time the westbound train enters section HT, relay HWTV becomes energized by a pick-up circuit passing from terminal B, through contact HTM-80, contact 65 of relay ZllRaI-I, and the Winding of relay HWTV to terminal N. Relay I'IWTV, upon becoming energized, closes its own stick circuit which is the same as the pick-up circuit just traced except that it includes con- 11 tact HWTV-S'I instead of contact 65 of relay 24RaH.

Relay HFSA, upon becoming deenergized, completes a circuit for energizing auxiliary transformer HXF, shown at the left-hand end of Fig. 1a, this circuit passing from terminal BX, through contact 8| of coding device |80CT, contact 82 of relay ZWH closed in the normal position, contact 83 of relay 2WH, contact 84 of lever HV, contact HFSA-BS, and primary Winding 'm of transformer HXF, to terminal NX.

When relay HWTV becomes energized, primary Winding m of transformer HWCF also becomes energized by a circuit which is the same as the circuit just traced for transformer HXF as far as contact HFSA-85, and which then passes through the front point of contact HWTV-86, and primary Winding m of transformer HWCF to terminal NX. With primary winding m of transformer HWCF now energized by current passing through contact 8| of coding device I80CT, cab signal control current coded at a frequencyof 180 times per minute is supplied to the rails of section HT from secondary winding d of transformer HWCF, through the front points of contacts ll and I2 of relay HWCTM during their closed periods. The cab signal of the westbound train on section HT therefore displays a corresponding proceed indication.

When the Westbound train enters the iirst section of track 2T West of section I'IT, relay 2WH becomes deenergized, and therefore its contact 83 opens the circuits previously traced forA energizing transformers HWCF and HXF, so that relay HWCTM becomes deenergized.

When the Westbound train leaves section HT, relay HTR again becomes energized by steady direct current as previously described for an eastbound train leaving section HT. With relay HTR energized, relay HFSA becomes energized, as previously described, causing relay HCTM in turn to become energized by steady direct current passing through the back point of contact 36 of relay I'JBSA. Relay HCTM then Yopens the circuit for relay I'ITR, causing relay HTR to become deenergized. Relay HBSA then becomes energized as previously described, and relay HCTM in turn becomes energized by its circuit through contact 34 of coding device MI8DCT. With relay HTR. now energizedvby coded current of 180 cycles per minute controlled by the back points of contacts I 'iCTM-B and HCTM-I, the apparatus is restored to its normal condition.

Relay HTM, upon becoming energized, opens the circuit previously traced for relay HWTV through contact HTM-80, thereby causing relay HWTV to be deenergized. With transformer HWCE1 thus deenergized, the Westbound cab signal control current previously supplied to section HT is discontinued.

The Winding of relay IQXFSA and the branch path including resistor 29 and asymmetric unit 30 in multiple with this Winding are proportioned so that if an unauthorized westbound train should enter section HT While switches H and EH are in the reverse position, the front con.- tacts of relay ISXFSA will open before the back contacts of relay HTM become closed.

We shall next assume that section HT becomes occupied by an eastbound light engine, andthat a momentary loss of shunt of the track circuit occurs. Relay HTR, therefore, first becomes energized by steady direct current, as previous,-

1y described, causing relay HFSA to also become energized. Relay HCTM is then energized, as previously described, causing relay HTR to again become deenergized, with the result that relay HBSA becomes energized. With relay I 'IBSA energized, the circuit for energizing relay HBSAM is closed, but this relay is slow picking up, so its contact 33 does not become closed until after the lapse of a brief period of time. If the loss of shunt period lasts long enough, the circuit for relay HTM will be closed through contact 33 of relay HBSAM. However, it is unlikely that a momentary loss of shunt will last long enough for relay HTM, which is also of the slow pick-up type, to close its front contacts.. The circuits controlled by relay HTM will therefore not be affected by a momentary loss of shunt.

We shall now assume that all parts of the apparatus are again in the normal condition, and that lever 26V is moved to its f position for controlling unit a of signal ZEL to display a proceed indication for an eastbound train, and that signal 26Lc is displaying a stop indication. We shall assume further that, While an eastbound train is approaching signal 22L, a second train overruns signal ZQLc, that is, it stops with its front Wheels on section 25T, so that relay 25TR becomes deenergized, causing relay 25TM in turn to also be deenergized. We shall refer to the rst train, which is given a proceed indication by signal 26L, as an authorized train, and We shall refer to the second train which is given a stop indication by signal 26Lc, as the unauthorized train.

With section ZIT not yet occupied by the authorized train, relay ZSXTR, as Well as relay 2|TR, Will still be energized. With lever 26V in its f position While relay 25XTR is energized, relay ZSXTM becomes energized by a pick-up circuit passing from terminal B, through contact 25XTR-81, resistor 29 and asymmetric unit 30 in multiple with the winding of relay 25XTM, and contact 28V-88 to terminal N. Relay 25XTM, upon becoming energized, closes its stick circuit, which is the same as the pick-up circuit just traced except that it includes contact 25XTM-89 instead of contact 26V-88. With relay ZSXTM energized, contact ZEXTM-ED becomes opened, causing relay 25S to be deenergized.

If, now, with relay 25S thus deenergized, and with relay 25TM deenergized by the unauthorized train, the authorized train passes signal 26L, cab signal relay 2ITV cannot become energized when back contact HTM-54 becomes closed, because contacts 25TM-92 and Z55-93 in the circuit for relay 2|TV are now open. Cab signal transformer 2ICF, therefore, remains deenergized, so that no cab signal control current is supplied to section 21T. The authorized train Will, therefore, not receive a proceed cab signal indication, but will receive a restrictive cab signal indication.

We shall next assume that, instead of the unauthorized train overrunning signal 25Lc before the authorized train passes signal ZSL, the authorized train passes signal 26L before the unauthorized train enters section 25T.

When the authorized train now enters sec tion 2|T, relay ZITV becomes energized by a circuit passing from terminal B, through contact 2|TM-64, contact 65 of relay Z'LaH, contact 25TM-92 in multiple with contact 25S-93, and the Winding of relay ZITV to terminal N. Relay 2| TV, upon becoming energized, completes its own stick circuit, which is the same as the 13 pick up circuit just traced except that it Aincludes contact ZITV-BI instead of contact 65' of relay 2BLaH With relay 2ITV energized, cab signal transformer 2ICF becomes energized by current passing from terminal BX, through Contact' SIIv of coding device EI30CT, front point of contact 3U-95, contact 96 of relay IEH closed inthe normal position, contact 9.1 of relay IEH, contacts 23TM-98 and HTM-99, Contact IOIl of lever 2ITV, front point of contact 2ITV-IOI, and primary winding m of transformer 2 ICF to terminal NX, With transformer 2ICF thus energized by current coded at a frequency of `180 times per minute, cab signal control current of this frequency is supplied to the rails of section 2 IT for controlling the cab signal of the authorized train to display a corresponding proceed cab signal indication.

If, now, the unauthorized train passes signal 26Lc deenergizing relay 25TM before the authorized train passes insulated joints 5 at resistor 25r and, therefore, While relay 25XTR is still energized, relay 25XTM is energized, and hence relay 25S is deenergized, and, therefore, relay 2ITV becomes deenergized due to relays 25S and 25TM being deenergized. With relay 2ITV thus Ideenergized, the cab signal current being supplied to section 2IT is discontinued, and the proceed cab signal indication is taken away from the authorized train.

If, however, the authorized train has proceeded far enough to deenergize relay 25XTR before the unauthorized train deenergizes relay 25TM, relay 25S Will become energized by its pick-up circuit, and will then remain energized by its stick circuit after the unauthorized train deenergizes relay 25TM. Contact 25S-93 will therefore remain closed in the stick circuit for relay 2ITV, so that cab signal control current will continue to be supplied to section 2 IT, and the authorized train will continue to receive a proceed cab signal indication.

We shall next assume that all parts of the apparatus are again in the normal condition and that switch lever ZIV is moved to its 1* position for effecting operation of switches 2l and E2! to their reverse position, and that lever 26V is moved to its f position, so that relays 26LbH and 20LJ are energized for controlling unit b 'of signal 26L to display a proceed indication while signal 24L is controlled to indicate stop.

If, now, an unauthorized train passes signal 24L before an authorized train passes signal 26L,

relays I'ITR and, in turn, I'ITM will be deenergized. With relay 2 IXTRI still energized, and with lever 2IV in its r position, relay ZIXTM will be energized by a circuit passing from terminal B, through contact 2IXTRI02, winding of relay ZIXTM in multiple with a resistor129 and an asymmetric unit 30, and contact ZIV-|03 to terminal N. With signal 24L controlled to indicate stop, relays 24LaH and 24LJ are both deener:

gized.

Since relay 2I XTM is, now energized, its contact 2IXTM-69 is open in one of the pick-up circuits for relay IITV. Contact ZITV-I is also open in the same 'pick-up circuitfor'relayTITV.

-Relay IITV therefore does not become energized when the unauthorized train passes signal 24L. The unauthorized train, therefore, receives a rev stricting cab signal indication.

When relay I'ITM becomes deenergized, its contact I I'I'l\/I-'I3 opens in the circuits for relay, I'ITS, and hence relay I 'ITS becomes deenergized. With relay |1TS deenergized, its contact HTS-41 is open in the circuits for relay 24LA, causing relay 24LA to also be deenergized.

If the authorized train passes signal 26-L before the unauthorized train passes signal 24L, relay 2ITV becomes energized by a circuit passing from terminal B, through contact 2ITM-64, contact of relay 26LbH, contact 9I of relay 26LJ, contact 25TM92 in multiple with contact 25S-93, and the Winding of relay 2ITV to terminal N. Cab signal transformer 2ICF is therefore now energized by current passing from terminal BX, through contact |04 of coding device EI20CT, contacts |05 and contact |06 of relay 2EH, contacts HTM-|01, 23TM-I08, and ISTM- I09, contact IIO of lever 2IV, front point of contact 2ITV-IOI`, and primary winding 'm of transformer 2 ICF to terminal NX. With current coded at a frequency of times per minute thus supplied to transformer 2ICF, cab signal current correspondingly coded is supplied to the rails of section 2 IT for controlling the cab signal onk the authorized train to display a corresponding proceed indication.

If, now, an unauthorized train passes signal 24L while the authorized train is on section 2 IT, contact HTM-|01 will open the circuit last previously traced for cab signal transformer ZICF,

thereby removing cab signal control current from section 2IT and causing the authorized train to receive a restricting cab signal indication.

If, however, the authorized train deenergizes relay 2 IXTR before the unauthorized train passes signal 24L, relay 2 IXTM will become deenergized, thereby completing a circuit for relay I'ITV passing from terminal B, through contacts HTM-64, MLA-68, ZIXTM-BS, 2ITV-'I0, and ZIV-ll, and the winding of relay I'ITV to terminal N. With relay IITV energized, current coded at a frequency of 120 times per minute will be supplied to cab signal transformer I'ICF by a circuit passing from terminal BX, through contact |04 of coding device EI20CT, contacts |05 and |06 of relay 2EH, contacts ZIV-I II and I1V'I6, contact 'I1 of lever IQV, front point of contact I'ITV-18, and winding m of transformer I'ICF to terminal NX. With cab signal current coded at a frequency of 120 times per minute thus supplied to section ITT, the authorized train will receive a corresponding proceed cab signal indication.

If, then, the unauthorized train enters section I'IT, relay I'ITV Will remain energized by its stick circuit, so the authorized train will continue to receive a proceed cab signal indication, and will shunt the track ahead of the unauthorized train, so that `the unauthorized train will receive a restrictive cab signal indication.

' In Fig. 2, track transformer I F is shown energized by current coded at a frequency of 75 times per minute in a circuit passing from terminal BX, through contact I I2 of coding devices 'I5CT, from point of contact II3 of relay BSA, back point of contact II`4 of relay 2H, and p-rimary winding m of transformer IF to terminal NX. Current coded at a frequency of 75 times per minute is .therefore supplied by transformer IF to block 1L-c. Code following relay XTR. is therefore energized and is repeatedly closing its contact 28 alternately at its front and back points. Relay FSA is therefore Yenergized by a circuit which includes the front point of contact 28 of relay XTR, and relay BSA is energized by a circuit passing from terminal B, through the back point of contact 28 of relay XTR., contact 3l of relay FSA, and the Winding of relay BSA in multiple with resistor'29 toV terminal N.

With the apparatus arranged as shown in Fig. 2, with signal 2S controlled to indicate stop, We shall assume that a .train moves from left to right, as shown in the drawing, which We shall also assume is the eastbound direction. When the train arrives at the code change point b, relay XTR becomes deenergized, causing relays FSA and BSA in turn to become deenergized. Cab signal control current, coded at a frequency of 75 times per minute, is therefore discontinued, so that the train, upon passing point b, receives a restricting cab signal indication.

When the train leaves block a-c, transformer IF first becomes energized by steady alternating current passing from terminal BX, through contact I'I5 of relay FSA, back point of contact II3 of relay BSA, back point of contact .I I4 of relay 2H, and winding m of transformer IF to terminal NX. Relay XTR, therefore, becomes steadily energized, causing relay FSA to become energizedy by its circuit previously described. Relay FSA, upon becoming energized, opens its contact II5, thereby deenergizing transformer IF and causing relay XTR to become deenergized. Relay BSA then becomes energized by its pick-up circuit previously traced, causing the circuit previously traced for transformer IF through contact II2 of coding device 'I5CT to again be closed. The operation of the apparatus at points b and c is therefore restored to the normal condition,

If relay 2H is controlled to be energized for clearing signal 2S, transformer IF is energized by current passing from terminal BX, through contact II'I of code transmitter ISOCT, contact II8 of relay 2TR, front point of contact IH of relay 2H, and winding m of transformer IF to terminal NX. Current coded at a frequency of 180 times per minute is therefore now supplied to block a-c for controlling the cab signal of a train in the block a-c to display a corresponding proceed indication. The train, upon moving through block a-c, will now have no change in cab signal indication when it passes point b and deenergizes relays FSA and BSA.

If the apparatus of Fig. 2 is modified as shown in Fig. 3, and if an eastbound train then passes point b, deenergizing relay BSA, primary winding m of transformer IF will be energized by current coded at a frequency to which cab signals will not respond, passing from terminal BX, through contact IZil of coding device XCT, contact I2I of relay EUBSA, back point of contact I|3 of relay BSA, back point of contact II4 of relay 2H, and winding m of transformer IF to terminal NX. When block a-c now becomes vacated, relay XTR will become energized by the coded current of a frequency to which cab signals will not respond, causing relays FSA and BSA to become energized and thereby again complete the circuit for transformer IF includingl contact I I2 of coding device 15CT. g

Although we have described the operation of the apparatus shown in the accompanying drawings for only a few typicaltrac movements, it is believed that, in view of these descriptions, the operation of the apparatus for any other possible traic movement can be traced readily by -reference to the drawings, without further description.

Although We have herein shown and described only a few forms of railway traic controlling apparatus embodying our invention, it is understood that various changes and modifications may be made therein Within the scope of the appended claims without departing from the spirit and scope ofthe appended claims without departing from the spirit and scope of our invention.

Having thus described our invention, what we claim is:

1. In railway traffic controlling apparatus embodying a coded track circuit for a track section within interlocking limits at an interlocking plant, in which said section is provided with a track circuit including a source of direct current connected across one end of the section and a code following track relay connected across the opposite end of the section for controlling wayside signals, in which a source of alternating current for controlling cab signals is connected across the same end of said section as said direct current source, the combination comprising, a rst detector relay controlled by a front contact of said track relay, a second detector relay controlled by a back contact of said track relay in series with a front contact of said rst detector relay, a slow pick-up relay controlled by a front contact of said second detector relay, a code repeater relay having a first energizing circuit controlled by a coding contact in series with a front contact of said second detector relay and having a second energizing circuit controlled by a front contact of said first detector relay in series with a back contact of said second detector relay, a back contact of said code repeater relay connected in series with said direct current source and with said alternating current source across the rails of its section, and means controlled by a back contact of said rst detector relay and by a back contact of said slow pick-up relay for supplying alternating current to the relay end of its section for controlling cab signals.

2. In railway traflic controlling apparatus embodying a coded track circuit for a track section within interlocking limits at an interlocking plant, in which said section is provided with a track circuit including a source of direct current connected across one end of the section and a code following track relay connected across the opposite end of the section for controlling wayside signals, in which a source of alternating current controlled by an approach stick cab' signal relay is connected across the same end of said section as said direct current source for controlling cab signals, the combination comprising, a rst detector relay controlled by a front contact of said track relay, a second detector relay controlled by a back contact of said track relay in series with a front contact of said first detector relay, a slow pick-up relay controlled by a front contact of said second detector relay, a code repeater relay having a rst energizing circuit controlled by a coding contact in series with a front contact of said second detector relay and having a second energizing circuit controlled by a front contact of said first detector relay in series with a back contact of said second detector relay, a back contact of said code repeater relay connected in series with said direct current source and with said alternating current source across the rails of its section, means controlled by a back contact of said slow pick-up relay and by control means for a wayside signal for said section and also by other traffic responsive means for controlling said cab signal relay to become energized and to remain energized only if no train occupies a route including said section in advance of a point at Which said train would conict with a given train controlled by said wayside signal for f said section .before saidfgiv'en train lpasses said `4point, and! means controlled by a front contact of vsaid cab-signal relay-for controlling said source "of alternating current forsupplying alternating ofl the section for controlling a wayside signal,

in which a source of alternating current for controlling cab signals is connected across the same end of the section as said direct current source,

4the 'combination comprising, a detector relay controlled by a front contact ofn Vsaid track relay, a second detector relay controlled by a back contact' of said track'relay in series with a front contact of vsaidiflrst detector relay, a code repeater relay having an energizing circuit controlled by acoding contact in series with a front contact of said second detector relay and having a secondenerg'izing circuit controlled by a front contact of said vrst detector relay in series with a back contact of .said second detector relay, a backcontact'of said code repeater relay connected in series with said directcurrent source and with said alternating current source across said one end of said section, an approach stick cab signal. relay having aVpick-up and a stick circuit each of which is .controlled by a contact which is closed if said second detector relay is deenergized and said-pick-.up circuit also controlled by a contact which is closed if a wayside signal for said one end of saidsection is controlled to display Va proceed indication, a cab signal transformer, an auxiliary transformer, means controlled by a back contact of said irst detector .relay and by a front contact of said cab signal relayV for energizing the primary winding ofsaid cab Vsignal transformer, means.- controlled by a back contact of said first detector relay for energizing said auxiliary transformer by coded current, a code following transfer relay energized from the secondary winding of said auxiliary transformer, a back contact of said transfer relay connected in series with the winding of said track relay across said section, and a front contact of said transfer relay connected in series with the secondary winding of said cab signal transformer across said section adjacent said track relay for controlling cab signals. l

4. In railway traffic controlling apparatus for a track section at an interlocking plant, in which said section is provided with a track circuit including a source of direct current connected across one end of the section and a code following track relay connected across the opposite end of the section for controlling a wayside signal, in which a source of alternating current for controlling cab signals is connected across the same end of the section as said direct current source, the combination comprising, a detector relay controlled by a front contact of said track relay, a second detector relay controlled by a back contact of said track relay in series with a front contact of said first detector relay, a, code repeater relay d having an energizing circuit controlled by a cod- -18 contact of said code repeater relay connected in series with said direct current source and with said alternating current source across said one end of said section.

5. In traic controlling apparatus for a section of railway track embodying a track .circuit for'said sectionl which includes a code following track relay connected across said section, the

vcombination comprising, a detector relay controlled by a front contact of said track relay, a second detector relay controlled'by a back contact of said track relay in series with a front contact'of said first detector relay, and means controlled by said first and second detector relays for supplying current of a given character to said section when saidv section becomes vacated after being occupied by a train' and controlled by a Vfront contact of said' second. detector relay for periodically supplying current of said given character to said section.

6. In track circuit apparatus for 'controlling traic governing means for a section of railway track, including a code following track relayconnected across said section,fthe' combination comprising, a detector relaycontrolled by a front contact of saidtrack relay, a second detector relay controlled by a back contact of said track relay in series with a front contact of said rst detector relay, means for supplying current of a given character to said'section for energizing said track relay when said section becomes vacated after being occupiedby a train, and means vcontrolled by a front contact of said second detector relay for supplying coded' current to said section.

7. In railwaytrafliccontrolling apparatus' for a track section at an interlocking plant, in which said section is provided' with a track circuit including a source of lcodedl direct current connected across one end-of the section and a code following track relay connected across the opposite end of the'sectionfor'controlling a wayside signal, in which a source of alternating current controlled in part by said code following track relay for controlling cab signals is connected across the same end of the section as said source of coded direct current, the combination comprising, an approach stick cab signal relay controlled to become energized if a train enters said one end of said section while a signal is indicating proceed for said train to enter'said section and to remain energized while said train occupies said section, and means controlled by a front contact of said cab signal relay while said track relay is deenergized by a train in said section for supplying alternating current to the track relay end of said section for controlling cab signals.

8. In a railway .traffic control system for two routes which converge at a switch in an interlocking plant, in which two wayside signals are provided one for each of said routes for governing trains entering the corresponding routes, the combination comprising, a track section embodied in one of said routes including said track switch, a second track section for the other route extending between said wayside signal for its route and said switch but not including said switch, a track circuit for said first section including a track relay connected across the rails adjacent its signal for controlling its signal and including a source of current connected across the opposite end, means controlled by a train upon entering the relay end of said rst track section for supplying proceed cab signal control current to said fpposite end, a iioater track relay facesse? "connected across the' rails of saidtrackcircuit ladjacent said switch andarranged to remain energizeduntil a trainoneither route arrives at a point adjacent said switch, and means conin response to a proceed indication of its wayside signal only if said train arrives at a point adjacent saidrswitch before a second train enters said second route;

9. In a railway traill'c control system for two routes which converge at a vswitch in an interlocking plant, in which two wayside signals are provided one for each of said routes for governing trains entering thevcorresponding routes, the

combination comprising, a trackV section embodied in one of said routes including said' track switch; a second track section `for therother route ',troll'ed by saidl floaterftrack relay for retaining proceed'cab signal control current for a train on said rst route lwhich has entered saidv rst route extending between said waysideA signal for its l 'route and said switchV but. not including said switch, a track circuit for said rst section in- -cluding a track relay` connected across theV rails adjacent its signal for controlling 'its' signal and across the rails of said track circuit adjacentfsaid switchand arranged to remain energized until a. train on either routearrives at a point adjacent said switch, a floaterlstick relay controlled to become energized if; the signal for said'vrst ergized while saidsecond track section is unoccupied; a cab signalmelayfcontrolled to become energized only if isaidsecond` track section is unoccupied or if said second iioater stick relay -includingv a source of currentconnected across' .the opposite end, a floater track relay connected is. energized,;and means controlledl by a fronty contactV of saidcab signalf relay *for supplying lcab signalcontrol currentzto said first. track section` 10.'In railway trame `controlling Vapparatus embodying track circuiti;y for a plurality of` track sections within interlocking limits at an interlocking plant, in which each section is provided with a track circuitv including a source of direct current connected'across one end of the section and a track relay connected across the opposite end of the section for controlling a wayside signal, the combination comprising, a first route including a iirst track section, a signal for governing trafiic movements onto said nrst route, a second route including'a secondsection between its entrance end and a point at which it converges into said rst route, a rst stick relay controlled to become energized when said signal is cleared and to then remain-energized until a train on either said iirst or said4 second route arrives adjacentv said point at whichsaid routes conv,erge,;a second stick relay controlled to become energizedY onlyif said first stick relay is deenergized and if said second section is unoccupied and to then remain energized as long as said ilrst stick relay is deenergized, a cab signal relay controlled to becomev energized if said first section becomes occupied while said signal is controlled to display a proceed indicationand if said Vsecondv section is unoccupied or said second stick relay is4 energized, and means controlled by said cab signal relay upon becoming energized for supplying cab signal control current to said irst section.

CHARLES W. FAILOR. JOHNR. HENDERSON.

REFERENCES CITED The following references are of record in the le -of this patent:

' UNITED STATES PATENTS Number Name Date Y Re. 22,841 Shields Feb. 11, 1947 1,629,187 Wallace May 17, 1927 1,692,061 Thompson Nov. 20, 1928 

